Derby Talk

I don't want to throw water on anyone's creativity or desire to reduce expenses, but I think the MicroWizard kit timers, which tell you order of finish without a computer, are pretty affordable in the ~ $50 - $60 territory (have to check current pricing). How much time/money is the Bosworth option t...

One other comment. Sometimes when you think that your drill press is no longer perfectly square - depending on your holding/drill method, the problem might be your wood. We used the variable angle plate method as well, which needs square pieces of wood. All of our blocks were first sorted on the dri...

I was real happy with the #93543 HF scales, and used one on each wheel at times. Their accuracy and repeatability, compared to even 3-beam scales, was amazing for the (often on sale) price. Our cars often had a row of 1/4" cubes in the very back so the cars usually stand up on the 'hind end' fo...

TPWQ, If I had to list the references that I appreciated the most as we were learning, I would say: David Meade's "Pinewood Derby Speed Secrets" book; the Pinewoodderbyphysics.com lectures; Stan's web pages; the "Physics and Pinewood Derby" video; the 'tool use hot-to' video's fr...

Congrats !
One question though, maybe I missed this, what was our wheelbase ? 3/4" is a pretty decent COMh for standard wheelbase cars (on center guided tracks). Beyond that, you have to have really good parts and prep and a good track.

Some quick thoughts: - Can you drill some wood out and decrease your COM from the rear axle ? - How good are your rear wheels ? Aside from alignment, having minimum out-of-round wheels (and I like smoothe spinners) is very important. - What wheel bore diameter do you have ? For oil lube cars we ran ...

I would say that after a very stressful month, you and your son had a GREAT Pinewood Derby. If your son left the race with enjoyment of the time you spent, appreciation for your interest in helping him and a positive attitude about the whole experience (despite the many flaws at the race) - then you...

FatSebastian wrote:These appear to be the basic rules that come in the box.

I see, but I still say, there is a ton of room there. You could make your own razor wheels, shape the tread into a point, etc., and meet that.

Not to detract from the main purpose of the thread though - good basic points from Stan.

Wow ! You could drive a 18-wheel truck through those rules ! :o You can do anything you want to the wheels, as long as they were originally BSA wheels. Depending on the attitude taken there could legally be cars in the race with 1 gram wheels from the pros. That would be a definite advantage, but po...

I've asked so many questions on my build in such a short time that I feel I've worn out my welcome. Hopefully not. No one is answering that doesn't want to, so no worries. :thumbup: Or 1.5 degrees on the DFW and 2.5 on the rears? Without a test track, that's a fairly typical setup. You can relax th...

This is where having some gauge pins really help. We sort the wheels first by bore diameter. We wanted the smallest and most similar bores in the rear (no more than a 0.0005" difference), assuming they were very good wheels (runout, spin test). Putting the tightest bores and largest diameter ax...

We have used sanding sealer a fair bit because we mix in some balsa in our cars (use a water/white glue mix for the thick insulation add-ons) - which really need it, and there always seemed to be some tougher to get paint on spots in the pine. Can't say we paid that much attention, but I would say w...

Our recent prep for oil/graphite is basically the same and went to 0.05 for both. In hindsight I think 0.3 micron was plenty far for graphite axles, but we were set up for it. I know that wet sandpaper is popular, but I followed Sporty on that one and judging the final product, I think it was the wa...

Last couple of years we inverted the wet/dry plan. We used sandpaper and cushioned micromesh dry, cleaned with a baby wipe, then lapping films wet, then Mothers M&A, another baby wipe, cotton string (ala Doc Jobe) and finally a leather shammy or selvyt cloth. I haven't noticed a real difference ...

Good to hear from you Randy ! I have seen 1.18" in the recent past at one scout race. I would say that a wheel OD limit is still uncommon in our area. My impression was that it was there to eliminate professionally prep'd (bought or home lathed) wheels. I don't think most Scout check-ins are eq...